High reduction belt-driven linear actuator

ABSTRACT

The disclosure provides apparatuses, systems, and methods for belt driven linear actuator systems.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional ApplicationNo. 62/555,944 filed Sep. 8, 2017, entitled “BLOCK AND TACKLE FOR FLATBELTS,” the entirety of which application is hereby incorporated hereinby reference.

TECHNICAL FIELD

The present disclosure relates to the design of linear actuator systemspowered by rotary motors and driven by modern steel-reinforcedpolyurethane flat belts.

BACKGROUND

Flat belts were invented to solve the issues that wire rope presents towire-rope based elevator systems, such as their requirement forlubrication, relatively low traction potential, and low service life.Advances in materials science produced a rugged, durable polyurethanejacket that encloses multiple wire ropes that are run in a parallelarrangement, allowing the use of smaller traction drums whilesimultaneously increasing service life expectations by 3× or more.Steel-reinforced polyurethane belts are high performing, durable, andmaintenance-free: A combination of traits that have rendered their rapidadoption across the elevator industry. They are now making their wayinto other oscillatory linear applications, such as scissor lifts, forktrucks, and gym equipment thanks to their ability to efficientlytransmit power without maintenance for an extended period of time.

Care must be taken when designing systems that rely upon flat belts, asthey are sensitive to fleet angle misalignments much like otherreinforced belt constructions. Small amounts of fleet angle that wouldbe otherwise perfectly acceptable to a wire-rope system aresignificantly more detrimental to belt-based systems. Rope-based blockand tackle designs offer the benefit the benefit of mechanical reductionbut introduce fleet angles to the reeving system, especially whenreductions higher than 4:1 are necessary. Ropes are known for theirtolerance to fleet angles, and thus have always performed well in suchsituations. Belts, on the other hand, cannot be easily applied to blockand tackle topologies, as even the slightest of fleet angles issufficient to substantially reduce expected system service life.

SUMMARY

In general, this disclosure relates to linear actuation systems that areconfigured for deployment with a flat belt system.

In one aspect of the disclosure, a linear actuator system includes anactuator chassis having a main drive axis. The system includes a firstplurality of sheaves coupled respectively to a first shaft coupled tothe actuator chassis. The first plurality of sheaves include sheaveshaving an axis of rotation that is coincident with the first shaft. Thesheaves in the first plurality of sheaves are spaced apart from oneanother by non-constant spacing. The sheaves in the first plurality ofsheaves have different sheave centerline diameters with respect to oneanother. The system includes a second plurality of sheaves coupledrespectively to a second shaft coupled to the actuator chassis. Thesecond plurality of sheaves include sheaves having an axis of rotationthat is coincident with the second shaft. The sheaves in the secondplurality of sheaves are spaced apart from one another by non-constantspacing, the sheaves in the second plurality of sheaves having differentsheave centerline diameters with respect to one another. At least one ofthe first shaft and the second shaft are configured to translate alongthe main drive axis. The first shaft and the second shaft are positionedalong the main drive axis and are offset with respect to one another bya static rotation angle about the main drive axis. Points at respectiveends of line segments extending along a geometric centerline of eachsheave in the first plurality of sheaves and the second plurality ofsheaves lie along a common circular profile orthogonal to the main driveaxis.

In certain implementations, the linear actuator system includes one ormore of the following additional features. The linear actuator systemmay include a flat belt extending from a first termination point, to andabout the first plurality of sheaves, to and about the second pluralityof sheaves, and to a second termination point. The linear actuatorsystem may include a driver configured to engage the flat belt. Thedriver may include an electric motor and/or one or more idler pulleys.The linear actuator system may include at least one an actuation shaftmovably coupled to the actuator chassis to translate along the maindrive axis. In some implementations, the designed geometric centerlineof at least 6 sheaves pierces a common circular profile of a certainsize, orthogonal to the main drive axis. Each sheave may have an axis ofrotation that is coincident with its mating shaft.

In one aspect of the disclosure, a belt driven linear actuator systemincludes an actuator chassis and an actuation shaft movably coupled tothe actuator chassis to translate along an axis. The system includes afirst plurality of outer sheaves and a second plurality of outer sheavescoupled respectively to a first outer shaft and a second outer shaft.The first plurality of outer sheaves and the second plurality of outersheaves are configured to rotate freely about the first outer shaft andthe second outer shaft, respectively. The first outer shaft and thesecond outer shaft are rotatably coupled to the actuator chassis andlaterally fixed with respect to the actuator chassis. The systemincludes a first plurality of inner sheaves and a second plurality ofinner sheaves coupled respectively to a first inner shaft and a secondinner shaft. The first plurality of inner sheaves and the secondplurality of inner sheaves are configured to rotate freely about thefirst inner shaft and the second inner shaft, respectively. The firstinner shaft and the second inner shaft are configured to translate alongan axis in the actuator chassis to drive the actuation shaft. The systemincludes a flat belt extending from a first termination point, to andabout: the first plurality of inner sheaves, the first plurality ofouter sheaves, the second plurality of inner sheaves, the secondplurality of inner sheaves, and to a second termination point. The firstouter shaft and the first inner shaft are tilted with respect to oneanother by a static rotation angle about the axis, and the second outershaft and the second inner shaft are tilted with respect to one anotherby the static rotation angle about the axis so as to eliminate fleetangles.

In certain implementations, the belt driven linear actuator systemincludes one or more of the following additional features. The beltdriven linear actuator system may include a redirection sheave coupledto the actuator chassis and configured to be coupled to a rotaryactuator. The flat belt may extend from the first termination point,then to and about the first plurality of outer sheaves, then to andabout the redirection sheave, then to about the second plurality ofinner sheaves, then to and about the second plurality of outer sheaves,and then to a second termination point. The belt driven linear actuatorsystem may include the rotary actuator. The rotary actuator may beconfigured to rotate back and forth. The actuator chassis may include ahousing cover positioned about the actuator chassis and at least aportion of the actuation shaft may translate into and out of the housingcover. The first inner shaft and the second inner shaft may beconfigured to translate along the axis in the same direction, whereby adistance between the first plurality of outer sheaves and the firstplurality of inner sheaves is configured to increase contemporaneouslywith a distance between the second plurality of outer sheaves and thesecond plurality of inner sheaves decreasing and whereby the distancebetween the first plurality of outer sheaves and the first plurality ofinner sheaves is configured to decrease contemporaneously with thedistance between the second plurality of outer sheaves and the secondplurality of inner sheaves increasing. The first inner shaft and thesecond inner shaft may be configured to oscillate along the axis. Thebelt driven linear actuator system may include the rotary actuatorcoupled to the redirection sheave. Each of the first plurality of outersheaves, the second plurality of outer sheaves, the first plurality ofinner sheaves, and the second plurality of inner sheaves comprisessheaves may having different diameters. The sheaves having differentdiameters may be parallel to one another. The spacing between parallelsheaves may be non-constant. The spacing between parallel sheaves maydecrease as the sheaves decrease in diameter. The belt driven linearactuator system may include thrust washers positioned between thesheaves to provide spacing between the parallel sheaves. The sheaves maydecrease in diameter axially outward.

Certain aspects provide methods of driving a belt driven linear actuatorsystem. The methods include energizing a rotary actuator coupleddirectly or indirectly to a flat belt according to one or more linearactuator system described herein.

Certain aspects provide methods of manufacturing a linear actuatorsystem according to one or more linear actuator system described herein.

Disclosed herein are methods, systems, and components for the design ofa flat belt based block and tackle design that is theoretically free offleet angles. A mapping technique forms a set of planar positions forthe centerlines of the free spans that provides a plurality of sheavegeometries, which reside on a common axis and spans that are free offleet angles at the sheave engagement interfaces. The present inventionpermits the use of high-performing flat belts in high-reduction (6:1 orgreater) block and tackle topologies, with the principal benefits of anextended service life, high power transmission efficiency, moreeffective traction power transfer, and a compact machine design.

One or two belt-based block and tackle topologies are combined with acapstan drive, in certain implementations, to form an electric linearactuator that is driven by an electric motor. The electric linearactuator may be used in hydraulic replacement applications, inconstruction equipment, material handling equipment, and manufacturingmachinery. These applications can include, but are not limited to,forklifts, stackers, dollies, man lifts, truck lifts, scissors lifts,motion simulation systems, and oil extraction equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

The skilled artisan will understand that the drawing primarily is forillustrative purposes and is not intended to limit the scope of theinventive subject matter described herein. The drawings are notnecessarily to scale; in some instances, various aspects of theinventive subject matter disclosed herein may be shown exaggerated orenlarged in the drawings to facilitate an understanding of differentfeatures. In the drawing, like reference characters generally refer tolike features (e.g., functionally similar and/or structurally similarelements).

FIG. 1 illustrates the prior art, a block and tackle reduction drivedriven by a reel system that contains fleet angles.

FIG. 2 depicts an isometric view of the linear actuator in its entirety.

FIG. 3 shows an isometric view of the main drive elements of thebelt-driven linear actuator.

FIG. 4 is an exemplary illustration of the output rod connections of theactuator.

FIG. 5 shows a detailed isometric view of the main structural elementsof the actuator.

FIG. 6 presents an isometric view of the isolated belt topology.

FIGS. 7A-7C are an exemplary illustration of the geometric techniqueused to prevent fleet angles in the free spans of the block and tackle.The point of view is taken to be along the main axis of the drive.

FIG. 7D-7E illustrates a machine design that avoids fleet angles viamethods of the prior art.

FIG. 8 depicts an axial view of the belt topology.

FIG. 9 shows an isometric view of an isolated belt-based block andtackle.

FIG. 10 depicts an isometric view of a cross section of an isolatedbelt-based block and tackle.

FIG. 11 shows a side view of the belt-based block and tackle,perpendicular to the axis of the right hand sheave set.

FIG. 12 shows a side view of the belt-based block and tackle,perpendicular to the axis of the left hand sheave set.

FIG. 13 presents the cross section of a sheave set that supports thebelt. The point of view is taken to be along the main axis of the drive.

FIG. 14 illustrates a side view of the belt topology near the motor endof the drive.

FIG. 15 shows a side view of the actuator in cross section.

FIG. 16 is an exemplary illustration of the means of termination of thebelt ends and the belt tension maintenance mechanism.

FIG. 17 shows a side view of the actuator.

FIG. 18 illustrates a separate species of the invention acts in tensiononly.

FIG. 19 provides a close-up of the frame structure of the separatespecies.

FIG. 20 shows the back side of the tension-only species of thisinvention, illustrating the belt topology.

FIG. 21 shows a complete isometric view of a tension-only implementationof this invention.

DETAILED DESCRIPTION

Following below are more detailed descriptions of various conceptsrelated to, and exemplary embodiments of, a block-and-tackle arrangementfor use with flat belts.

FIG. 1 illustrates a flat belt used in a conventional block-and-tackletopology described in U.S. Pat. No. 8,714,524 B2. Two parallel shafts 76and 106 contain a plurality of sheaves over which a flat belt 120 isrun. One end of the belt is fixed at a termination 122 while the otherend of the flat belt is driven by a reel 121. All sheaves are free torotate about their respective shafts with the exception of the reel,which is driven by the motor 114. The mechanical reduction as seen atthe reel of such a system is significant and is equivalent to the numberof free spans in the system, which in this instance is 10.Block-and-tackle methods are employed commonly with wire rope ratherthan with flat belts, due to the fleet angles (“kinks”) in the belt thatwould occur at each of the sheave interfaces, caused by the fact thatthe free spans 128 are not horizontal. This non-ideal geometricsituation results in either an asymmetric tension distribution withinthe reinforcing strands and/or sliding action between the belt and thesheave. Premature belt failure will occur due to sidewall abrasion andstrand fatigue. The reeling system, which processes sections of the beltthat are subjected to the highest number of bending cycles, is the mostlikely area for belt failure to occur. Not only are fleet angles presentin this design, but they vary as the distance between the principaldrive shafts 76 and 106 varies through the machine's range of travel.While this system may work in limited circumstances, the belt'sperformance, as measured by overall tension, sheave pressure, andservice life will be compromised in comparison to a wire rope that issubjected to the same topology.

FIG. 2 shows the overall form of the present invention. The actuator 201consists of an outer chassis 202 which may be configured in the form ofa housing body and a driving shaft 203 that extends and retracts withrespect to the outer chassis, which may be retract, at least in part inthe outer chassis 202. Mounting hardware 204 and 205 are positioned theouter chassis and the driving shaft 203, respectively, allowing power tobe supplied to those points. The actuator is driven by a motor 206(e.g., an electric motor).

FIG. 3 depicts the principal working elements of the actuator 201. Aunitary flat belt 301 is run around four main pluralities of sheaves308, 309, 310, and 311 that are rotatably coupled to four main driveshafts 302, 303, 304, and 305. The outer drive shafts 304 and 305 arefixed with respect to the chassis 202, while the inner drive shafts 302and 303 are free to travel along the main axis 307 by the prismaticcoupling created by the chassis 202 and the driving shaft 203.

FIG. 4 illustrates the structure involved in transmitting an axial loadfrom the mounting hardware 205 to the inner drive shafts 302 and 303.The output shaft 203 can be configured as a hollow shaft. The outputshaft 203 connects the mounting hardware 205 to the inner drive shafts302 and 303 by means of rigid inserts 402, rendering a fixed assembly ofcomponents that constitutes the power frame.

FIG. 5 presents the structure associated with the fixed frame.Semi-circular members 501, 502 are components of the outer chassis 202that connect the outer drive shaft 304 to the rest of the chassis base.Thus, tension can be generated in both directions between the fixedshafts 304 and 305 and the power frame shafts 302 and 303, which movewith respect to the fixed shafts 304 and 305 and with respect to andwithin the outer chassis 202.

FIG. 6 illustrates the belt topology in its entirety. A single flat beltbody 301 begins at a wedge termination geometry 601 that is nearly fixedwith respect to the outer chassis 202. The belt 301 is wound over aplurality of sheaves 308, rotatably coupled to shaft 302, and is woundover a plurality of sheaves 311, rotatably coupled to shaft 305, causingthe arced belt geometries 602 a-e and 604 a-d. Free spans 603 a-j jointhe arced sections of belt in order to fully constitute a block andtackle arrangement. The belt is then wound over a redirection sheave toform an arc 605 that leads to the drive unit. The drive unit is afriction drive component, consisting of a friction drum and an idlerthat opposes it. Multiple belt sections 606 a-c reside on the tractiondrum 1501, while additional arc sections 607 a, b reside on an idler1503 that rotates freely. Exiting the drive unit, the belt arc 608provides redirection along span 614 to the opposite block and tacklewhere it is wound around two pluralities of sheaves 309 and 310 that arefreely rotatable about shafts 303 and 304, respectively. These form arcsections 609 a-f and 611 a-e, connected by free spans 610 a-j. Exitingthe second block and tackle, the belt runs along free span 612, whichleads to wedge termination point 613.

Under running conditions, one block and tackle expands, while the othercontracts. The tension differential between the two sets is equivalentto the external load imposed upon the system, and the difference in belttension from the high-tension side to the low-tension side is suppliedby a friction drive, which will be described later. It should be notedthat in this exemplary embodiment of the invention, two block andtackles oppose each other for bi-directional load capability. Otherembodiments of the invention that require single-acting capability mayonly require one block and tackle (see, FIG. 18), with excess belt thatis released from the capstan drive being driven into a low tensiontake-up reel.

FIGS. 7A-7B are exemplary illustrations of the geometric technique usedto prevent fleet angles in the block and tackle arrangement. In thisfigure, we are looking down the principal motion axis of three distinctblock and tackle species with the centerline of the belt or ropeillustrated in each case. FIG. 7A represents a conventionalblock-and-tackle arrangement. FIG. 7B presents a modifiedblock-and-tackle design that eliminates fleet angles via a simple tiltmethod. FIG. 7C represents the geometric mapping technique hereindescribed that allows for common axes of both sets of sheaves while alsoeliminating fleet angles. FIG. 7D-7E present a machine design based onthe technique depicted in FIG. 7B.

A conventional block and tackle similar to that which is depicted inFIG. 1 will have a projection similar to the left-most illustration,consisting of two sets of sheaves of equal diameter that reside on axes705 which are parallel and from the mentioned projection angle willappear to be coincident. The first set of sheaves will render arcedsections of the flexible tensile member which when seen from theprojection of the axis mentioned will appear as vertical lines 701 a, b,c. Note that only six free spans are illustrated here for the purpose ofsimplicity. The second set of sheaves will render arced sections of theflexible tensile member's centerline which when seen from mentionedprojection angle will appear as vertical lines 702 a, b, c. Free spans703 a, b, c run from the first set of sheaves to the second set ofsheaves, and free spans 704 a, b run from the second set of sheaves backto the first. These free spans, analogous to the free spans 128 fromFIG. 1, are not parallel to the main axis and thus have a lateralcomponent that can be seen from this perspective. The presence of thislateral component is indicative of the fleet angle that is evident atany entry point into a sheave.

To adapt a block-and-tackle for use with a flat belt, we must get rid ofthe fleet angles. This is readily accomplished by simply tilting each ofthe sheaves and their corresponding belt arcs 707 a-c as per FIG. 7B andFIGS. 7D and 7E, such that the horizontal aspect of the free spanshrinks to zero.

In this species, all sheaves are tiled by the same angle such that fleetangles disappear. The opposing set of sheaves will create centerlineprojections 708 a-c. This accomplishes a zero-fleet angle condition, butrenders the rotation axes 706 a-c of the sheaves to be no longercoincident. Thus, a supporting shaft would have to have multiplenon-coincident shaft sections that support the sheaves.

FIGS. 7D and 7E depict a machine design that is based upon thisprinciple of fleet angle elimination. As can be seen, the supportingshafts (with centerlines 706 ac) are not coincident with each other oneither end of the block and tackle. This machine, designed by RolandVerreet and Jean-Marc Teissier, tests bending fatigue in wire ropesamples. By cleverly controlling the amount of stroke, certain sectionsof rope are subjected to an array of fractions of the maximum number ofbending cycles. Thus, by running the machine just once, an operator canascertain the condition of wear of the rope at 20%, 40%, 60%, 80%, and100% of the maximum number of bending test cycles. In the case of thismachine, the additional machine width generated by the method of fleetangle elimination is acceptable, and the sheaves are by necessity thesame size for the purposes of comparable testing information.

The present invention does not require the sheaves to be of exactly thesame size, and it is of paramount importance that the overall machinecompactness and the continuity of support shafts is maintained. This isaccomplished in the illustration of FIG. 7C. The geometry can be foundvia a mapping technique, starting with the sheave axes 709 and 710,which reside on opposite ends of the block and tackle. An initial sheavedimension 711 a and its axial span positions is drawn on its axis 710first, with each subsequent centerline arc (712 a, then 711 b, 712 b,711 c, 712 c, and so on) being defined by its predecessor and itsperpendicularity and centeredness on its own shaft. There is only onegeometric solution to the sheave set given a set of sheave axes 709,710, an initial centerline arc geometry 711 a, and a number of sheavesto generate. The resultant planar locations of the free span centerlinesas seen from this perspective reside along a circular profile 713 withthe additional constraints mentioned. Spacing between parallel sheavesis necessarily non-constant and decreases as the sheaves decrease indiameter toward the peripheries.

FIG. 8 shows an axial view of the belt topology, highlighting therotational axis 801 of outer shaft 305 and its respective set of freelyrotating sheaves 311. Belt sections 604 a-d reside on the plurality ofsheaves 311, in accordance with the positions shown in FIG. 7.

The plurality of sheaves 308 rotates freely about shaft 302, with itsaxis 802. Belt sections 602 a-e reside on the plurality of sheaves 308in accordance with the positions depicted in FIG. 7.

FIG. 9 shows an isometric view of a complete block and tackle topology.Arced geometries 609 a-f and 611 a-e are joined by free spans 610 a-j.

FIG. 10 shows a cross section of the block and tackle topology,including the free spans 612 and 614, which lead to wedge termination613 and redirection bend 608, respectively. Circular profile 713 isdrawn, intersecting the center-point of each belt segment in the crosssection.

FIG. 11 and FIG. 12 offer side views of the block and tackle topologyfor clarity.

FIG. 13 illustrates a cross section of the plurality of sheaves 308,which consists of five individual sheaves 1301 a-e, all of which rotateat different speeds and are freely rotating about shaft 303. The sheaveshave separating thrust washers 1302 a-f that allow for a compressiveaxial load of the sheave stack. Seals 1303 a-d maintain the greasedbearing volume and exclude possible contaminants. Belt segments 611 a-ereside on the plurality of sheaves 308. Output rod inserts 402 a and 402b provide a mechanical connection between the power frame shafts 302,303and the output rod 203.

FIG. 14 depicts a side view of the belt topology in the vicinity of thedriving motor for clarity.

FIG. 15 shows the supporting structure of many components in crosssection. The motor 206 and its gearbox 1502 are fixed to the tractiondrum 1501, which drives belt segments 606 a-c. Belt segments 607 a, breside on idler drum 1503, which is freely rotatable about its supportshaft 1505. The base frame 1504 fixes these components in place.

FIG. 16 illustrates a cross section view of the tensioning mechanism forthe terminations of the belt. Belt wedge geometry 613 is compressedbetween wedge 1601 and support walls 1602 a, b. The support walls 1602a, b are part of the termination body 1603, which is compressing acompression spring 1605 against the termination housing 1604. An idlerpulley is used to change a direction of the belt from the terminationpoint toward the sheaves. The termination housing 1604 is affixed to thebase frame 1504. In normal operation, the termination body 1603compresses against the base frame 1504 as high tension is developed inthe belt. If low belt tension develops during operation, the compressionspring 1605 forces the termination body 1603 outward, maintaining belttension at all times and allowing the traction drum 1501 to function bydoing so.

FIG. 17 illustrates a complete side view of many base components forclarity.

FIG. 18 shows an alternate species of the invention that relies on justone set of block and tackle. The belt, after exiting the first block andtackle and the drive unit, is spooled onto a reel. The plurality ofsheaves 1801 is analogous to sheave set 311, and plurality of sheaves1802 is analogous to sheave set 310. Drive sheave 1803 is analogous todrive sheave 1501 from the previous species, and idler sheave 1804 isanalogous to idler sheave 1503.

FIG. 19 presents a detailed view of the drive elements. The belttopology remains identical through the first block and tackle, theredirection sheave, and the drive unit. Belt arc segments 1901 a-c areanalogous to belt arc segments 606 a-c, and belt arc segments 1902 a, bare analogous to 607 a, b. When the belt exits the drive area, it isredirected by sheave 1903 onto a take-up reel instead of beingredirected to the opposing block and tackle. The spool 1904 may bepowered by spring or by active mechanical means.

FIG. 20 presents a detailed view of the belt topology of the secondspecies of the invention. Belt arc segment 2001 resides on redirectionsheave 1903, with free span 2002 leading to the spooled belt 2003.

FIG. 21 shows an isometric view of the second species. Free spans 2100a-j support the tensile load through the actuator, similar to any otherblock and tackle based lifting apparatus. The belt is driven through thecapstan friction-based drive unit comprised of drive sheave 1803 andidler sheave 1804. After exiting the drive unit, the belt is redirectedby sheave 1903 to the reel 1904 for storage at low tension. The majorityof the power flow through the system goes through the capstan drivesheave 1803 and into the rotary actuator.

As utilized herein, the terms “approximately,” “about,” “substantially”and similar terms are intended to have a broad meaning in harmony withthe common and accepted usage by those of ordinary skill in the art towhich the subject matter of this disclosure pertains. It should beunderstood by those of skill in the art who review this disclosure thatthese terms are intended to allow a description of certain featuresdescribed without restricting the scope of these features to the precisenumerical ranges provided. Accordingly, these terms should beinterpreted as indicating that insubstantial or inconsequentialmodifications or alterations of the subject matter described and areconsidered to be within the scope of the disclosure.

It should be noted that the term “exemplary” as used herein to describevarious embodiments is intended to indicate that such embodiments arepossible examples, representations, and/or illustrations of possibleembodiments (and such term is not intended to connote that suchembodiments are necessarily extraordinary or superlative examples).

For the purpose of this disclosure, the term “coupled” means the joiningof two members directly or indirectly to one another. Such joining maybe stationary or moveable in nature. Such joining may be achieved withthe two members or the two members and any additional intermediatemembers being integrally formed as a single unitary body with oneanother or with the two members or the two members and any additionalintermediate members being attached to one another. Such joining may bepermanent in nature or may be removable or releasable in nature.

It should be noted that the orientation of various elements may differaccording to other exemplary embodiments, and that such variations areintended to be encompassed by the present disclosure. It is recognizedthat features of the disclosed embodiments can be incorporated intoother disclosed embodiments.

It is important to note that the constructions and arrangements ofspring systems or the components thereof as shown in the variousexemplary embodiments are illustrative only. Although only a fewembodiments have been described in detail in this disclosure, thoseskilled in the art who review this disclosure will readily appreciatethat many modifications are possible (e.g., variations in sizes,dimensions, structures, shapes and proportions of the various elements,values of parameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter disclosed. For example,elements shown as integrally formed may be constructed of multiple partsor elements, the position of elements may be reversed or otherwisevaried, and the nature or number of discrete elements or positions maybe altered or varied. The order or sequence of any process or methodsteps may be varied or re-sequenced according to alternativeembodiments. Other substitutions, modifications, changes and omissionsmay also be made in the design, operating conditions and arrangement ofthe various exemplary embodiments without departing from the scope ofthe present disclosure.

All literature and similar material cited in this application,including, but not limited to, patents, patent applications, articles,books, treatises, and web pages, regardless of the format of suchliterature and similar materials, are expressly incorporated byreference in their entirety. In the event that one or more of theincorporated literature and similar materials differs from orcontradicts this application, including but not limited to definedterms, term usage, describes techniques, or the like, this applicationcontrols.

While various inventive embodiments have been described and illustratedherein, those of ordinary skill in the art will readily envision avariety of other means and/or structures for performing the functionand/or obtaining the results and/or one or more of the advantagesdescribed herein, and each of such variations and/or modifications isdeemed to be within the scope of the inventive embodiments describedherein. More generally, those skilled in the art will readily appreciatethat all parameters, dimensions, materials, and configurations describedherein are meant to be exemplary and that the actual parameters,dimensions, materials, and/or configurations will depend upon thespecific application or applications for which the inventive teachingsis/are used. Those skilled in the art will recognize, or be able toascertain using no more than routine experimentation, many equivalentsto the specific inventive embodiments described herein. It is,therefore, to be understood that the foregoing embodiments are presentedby way of example only and that, within the scope of the appended claimsand equivalents thereto, inventive embodiments may be practicedotherwise than as specifically described and claimed. Inventiveembodiments of the present disclosure are directed to each individualfeature, system, article, material, kit, and/or method described herein.In addition, any combination of two or more such features, systems,articles, materials, kits, and/or methods, if such features, systems,articles, materials, kits, and/or methods are not mutually inconsistent,is included within the inventive scope of the present disclosure.

Also, the technology described herein may be embodied as a method, ofwhich at least one example has been provided. The acts performed as partof the method may be ordered in any suitable way. Accordingly,embodiments may be constructed in which acts are performed in an orderdifferent than illustrated, which may include performing some actssimultaneously, even though shown as sequential acts in illustrativeembodiments.

All definitions, as defined and used herein, should be understood tocontrol over dictionary definitions, definitions in documentsincorporated by reference, and/or ordinary meanings of the definedterms.

The indefinite articles “a” and “an,” as used herein in thespecification and in the claims, unless clearly indicated to thecontrary, should be understood to mean “at least one.”

The phrase “and/or,” as used herein in the specification and in theclaims, should be understood to mean “either or both” of the elements soconjoined, i.e., elements that are conjunctively present in some casesand disjunctively present in other cases. Multiple elements listed with“and/or” should be construed in the same fashion, i.e., “one or more” ofthe elements so conjoined. Other elements may optionally be presentother than the elements specifically identified by the “and/or” clause,whether related or unrelated to those elements specifically identified.Thus, as a non-limiting example, a reference to “A and/or B”, when usedin conjunction with open-ended language such as “comprising” can refer,in one embodiment, to A only (optionally including elements other thanB); in another embodiment, to B only (optionally including elementsother than A); in yet another embodiment, to both A and B (optionallyincluding other elements); etc.

As used herein in the specification and in the claims, “or” should beunderstood to have the same meaning as “and/or” as defined above. Forexample, when separating items in a list, “or” or “and/or” shall beinterpreted as being inclusive, i.e., the inclusion of at least one, butalso including more than one, of a number or list of elements, and,optionally, additional unlisted items. Only terms clearly indicated tothe contrary, such as “only one of” or “exactly one of,” or, when usedin the claims, “consisting of” will refer to the inclusion of exactlyone element of a number or list of elements. In general, the term “or”as used herein shall only be interpreted as indicating exclusivealternatives (i.e. “one or the other but not both”) when preceded byterms of exclusivity, such as “either,” “one of,” “only one of” or“exactly one of” “Consisting essentially of,” when used in the claims,shall have its ordinary meaning as used in the field of patent law.

As used herein in the specification and in the claims, the phrase “atleast one,” in reference to a list of one or more elements, should beunderstood to mean at least one element selected from any one or more ofthe elements in the list of elements, but not necessarily including atleast one of each and every element specifically listed within the listof elements and not excluding any combinations of elements in the listof elements. This definition also allows that elements may optionally bepresent other than the elements specifically identified within the listof elements to which the phrase “at least one” refers, whether relatedor unrelated to those elements specifically identified. Thus, as anon-limiting example, “at least one of A and B” (or, equivalently, “atleast one of A or B,” or, equivalently “at least one of A and/or B”) canrefer, in one embodiment, to at least one, optionally including morethan one, A, with no B present (and optionally including elements otherthan B); in another embodiment, to at least one, optionally includingmore than one, B, with no A present (and optionally including elementsother than A); in yet another embodiment, to at least one, optionallyincluding more than one, A, and at least one, optionally including morethan one, B (and optionally including other elements); etc.

In the claims, as well as in the specification above, all transitionalphrases such as “comprising,” “including,” “carrying,” “having,”“containing,” “involving,” “holding,” “composed of,” and the like are tobe understood to be open-ended, i.e., to mean including but not limitedto. Only the transitional phrases “consisting of” and “consistingessentially of” shall be closed or semi-closed transitional phrases,respectively, as set forth in the United States Patent Office Manual ofPatent Examining Procedures, Section 2111.03.

The claims should not be read as limited to the described order orelements unless stated to that effect. It should be understood thatvarious changes in form and detail may be made by one of ordinary skillin the art without departing from the spirit and scope of the appendedclaims. All embodiments that come within the spirit and scope of thefollowing claims and equivalents thereto are claimed.

1-21. (canceled)
 22. A linear actuator system comprising: an actuatorchassis having a main drive axis; a first plurality of sheaves coupledto a first shaft coupled to the actuator chassis, the first plurality ofsheaves comprising sheaves having an axis of rotation that is coincidentwith the first shaft, the sheaves in the first plurality of sheaveshaving different sheave diameters with respect to one another; and asecond plurality of sheaves coupled respectively to a second shaftcoupled to the actuator chassis, the second plurality of sheavescomprising sheaves having an axis of rotation that is coincident withthe second shaft, the sheaves in the second plurality of sheaves havingdifferent sheave diameters with respect to one another, wherein at leastone of the first shaft and the second shaft is configured to translatealong the main drive axis, wherein the first shaft and the second shaftare oriented perpendicularly to the main drive axis and are offset withrespect to one another by a rotation angle about the main drive axis.23. The linear actuator system of claim 22, further comprising a flatbelt extending from a first termination point, to and about the firstplurality of sheaves, to and about the second plurality of sheaves, andto a second termination point.
 24. The linear actuator system of claim23, wherein the second termination point is within a take-up reel. 25.The linear actuator system of claim 23, further comprising a driverconfigured to engage the flat belt.
 26. The linear actuator system ofclaim 25, wherein the driver comprises an electric motor.
 27. The linearactuator system of claim 25, wherein the driver comprises a capstan, andwherein the flat belt takes at least two turns around the capstan. 28.The linear actuator system of claim 22, further comprising at least oneactuation shaft movably coupled to the actuator chassis to translatealong the main drive axis.
 29. A method of driving a belt driven linearactuator system, the method comprising: energizing a rotary actuatorconnected to a redirection sheave to rotate the redirection sheave, theredirection sheave coupled to an actuator chassis, the actuator chassiscomprising: a first plurality of sheaves coupled to a first shaftcoupled to the actuator chassis, the first plurality of sheavescomprising sheaves having an axis of rotation that is coincident withthe first shaft, the sheaves in the first plurality of sheaves havingdifferent sheave diameters with respect to one another; and a secondplurality of sheaves coupled respectively to a second shaft coupled tothe actuator chassis, the second plurality of sheaves comprising sheaveshaving an axis of rotation that is coincident with the second shaft, thesheaves in the second plurality of sheaves having different sheavediameters with respect to one another, wherein at least one of the firstshaft and the second shaft is configured to translate along the maindrive axis, wherein the first shaft and the second shaft are orientedperpendicularly to the main drive axis and are offset with respect toone another by a rotation angle about the main drive axis.
 30. Themethod claim 29, the actuator chassis further comprising a flat beltextending from a first termination point, to and about the firstplurality of sheaves, to and about the second plurality of sheaves, andto a second termination point.
 31. The method of claim 30, wherein thesecond termination point is within a take-up reel.
 32. The method ofclaim 30, further comprising a driver configured to engage the flatbelt.
 33. The method of claim 32, wherein the driver comprises anelectric motor.
 34. The method of claim 32, wherein the driver comprisesa capstan, and wherein the flat belt takes at least two turns around thecapstan.
 35. The method of claim 29, the actuator chassis furthercomprising at least one actuation shaft movably coupled to the actuatorchassis to translate along the main drive axis.
 36. A method ofmanufacturing a belt driven linear actuator system, the methodcomprising: movably coupling an actuation shaft to an actuator chassis;the actuation shaft movably coupled to the actuator chassis to translatealong a main drive axis; coupling a first plurality of sheaves to theactuator chassis, the first plurality sheaves coupled to the actuationchassis via a first shaft, the first plurality of sheaves configured torotate freely about the first shaft, the first shaft rotatably coupledto the actuator chassis and fixed in position with respect to theactuator chassis, wherein the sheaves in the first plurality of sheaveshave different sheave diameters with respect to one another; andcoupling a second plurality of sheaves to the actuator chassis, thesecond plurality of sheaves coupled to the actuation chassis via asecond shaft, the second plurality of sheaves configured to rotatefreely about second shaft, the second shaft configured to translatealong the main drive axis in the actuator chassis to drive the actuationshaft, wherein the sheaves in the second plurality of sheaves havedifferent sheave diameters with respect to one another, and wherein thefirst shaft and the second shaft are oriented perpendicularly to themain drive axis and are offset with respect to one another by a rotationangle about the main drive axis.
 37. The method of claim 36, furthercomprising extending a flat belt extending from a first terminationpoint, to and about the first plurality of sheaves, the second pluralityof sheaves, and to a second termination point.
 38. The method of claim37, wherein the second termination point is within a take-up reel. 39.The method of claim 37, further comprising coupling a driver configuredto engage the flat belt.
 40. The method of claim 39, wherein the drivercomprises an electric motor.
 41. The method of claim 39, wherein thedriver comprises a capstan, and wherein extending the flat beltcomprises the flat belt taking at least two turns around the capstan.